Moistureproof article



Patented Nov. 9, 1937 PATENT orncs MOISTUREPROOF ARTICLE William HaleCharch, Buffalo, N. Y., and Merlin Martin Brubaker and Frederick M.Meigs, Wilmington, Del., ments, to E. I.

assignors, du Pont de Nemoun & Com

by mesne assignn ny. Wilmington, Del., a corporation of Delil- NoDrawing. Application December 21, 1984, Serial No. 758,658

Claims.

This invention relates to the art of moistureproofing. Moreparticularly, it relatesto a composition of matter suitable fortheproduction of moistureproof materials and also to the mois- 6 tureproofmaterials per se. 1

We believe that moistureproofing is due to (l) the use of an agent whichis inherently moistureproof, and (2) the laying down of this agent in acontinuous unbroken film, either alone or 10 'in combination with othermaterials or vehicles hereinafter called film-forming substances.

We have found, as a result of a large number of experiments, thatsubstances are inherently moistureproof when they are of such a naturethat they are not only insoluble in water but also dissolve none or atleast only an infinitesimal amount of water. Apparently, water vapordiffuses through continuous unbroken films of such substances by aprocess of dissolving in the film and evaporating from the other side.The solubility of water in the moistureproofing agent -largelydetermines the rate of transfusion of water vapor through ,the film, andtherefore its inherent moistureprooiness. Obviously, if the film isnon-continuous and broken, otherfactors enterinto the determination of.the degree of moistureproofness.

We have found that ketones of the type hereafter more fully describedcan be used in the preparation of moistureproofing compositions whichwill yield moistureproof films, i. e. coatings or self-sustaining filmswhich are preferably also transparent, glossy, non-tacky, flexible,

possess good surface slip, etc.

For the purposes of this specification and claims, we definemoistureproof materials as those which, in the form of continuousunbroken sheets or films, permit the passage of not more than 5'70 gramsof water vapor per 100- square 40 meters per hour, over a period of 24hours, at

approximately 35 0.10.2" C., the relative humidity of the atmosphere atone side of the film ,being maintained at least at 98% and the relativehumidity of the atmosphere at the other side being maintained at such avalue as to give a humidity differential of at least 95%.

Moistureproofing coating compositions are defined as those whlch, whenlaid down in the form of a thin, continuous, unbroken film ap- 50, plieduniformly as a coating with a total coating thickness not exceeding0.0005" to both sides of a sheet of regenerated cellulose of thicknessapproximately 0.0009", will produce a coated product which ismoistureproof.

55 For the purpose of experimental tests, especially for those materialsadaptable as coating compositions, moistureproof materials include thosesubstances,. compounds or compositions which,- when laid down in theform of a continuous unbroken film applied uniformly as a coating with 5a total coating thickness not exceeding 0.0005" to both sides of a sheetof regenerated cellulose of thicknessapproximately 0.0009, will producea coated sheet which will permit the passage therethrough of not morethan 570 grams of 10 water vapor per 100 square meters per hour over aperiod of approximately 24 hours, at a temperature of 35 C.:0.2 0., witha water vapor pressure differential of 40-44 mm. (preferably 41.8i0.7mm.) of mercury. For convenience, the 15 number of grams of water vaporpassed under these conditions may be referred to as the permeabilityvalue. An uncoated sheet of regener ated cellulose having a thickness ofapproximately 0.0009" will show a permeability value of the order of5700.

From the foregoing, it is apparent that under the conditions set forth,a moistureproofed regenerated cellulose sheet is capable of resistingthe passage of moisture or water vapor therethrough at least 10 times aseffectively as the uncoatedregenerated cellulose sheet.

We have specifically defined herein moistureproofness in terms of apermeability test performed at substantially 35 C. It is to beunderstood, however, that by the adoption of this condition nodisclaimer is made of moi'stureproofness of any of the materials orcompositions when tested at temperatures lower than 35 C. Likewise, nodisclaimer is made of moistureproofing effects exhibited. by thematerials herein described at temperatures above 35 C: There will be atemperature for each moistureproofing agent above which neither it norcompositions containing it show substantial resistance to the passage ofmoisture. However, this behavior does not,

disqualify the materials herein described as moistureproofing agents.

The critical temperature above which these agents no longer exhibitmoistureproof properties is dependent primarily uponv the melting pointof the material and upon the nature and composition of the film-formingsubstance with which it is used. Agents of higher melting points willshow moistureproof properties up to higher temperatures than will agentsof low melting points, other conditions being, equal. Generallyspeaking, the agents of higher melting points will be preferred for thisreason though for moistureproof films, i. e. self-sustaining films orcoatings containing ketones which impart moistureproofness thereto, saidfilms being preferably also transparent, flexible, glossy, non-tacky,and possessing good surface slip.

Other objects will become apparent from the following description andappended claims.

The instant invention in one phase thereof contemplates a fiowablecomposition of matter which will deposit a molstureproof film, i. e.selfsustaining film or coating which, in the preferred embodiment, istransparent (glass-clear), flexible, glossy, non-tacky, and possessesgood sur-.

face slip. The composition consists of an agent which affords the basisfor moistureproofness and a film-forming substance. In the preferredembodiment, the composition also includes a solvent or solvent mixture,a plasticizer and/or a blending agent.

As the agents which afford the basis for the moistureproofness, theinstant invention contemplates solid organic ketones which areinherently moistureproof and have a melting point of at least 37 C. Themolecule of the moistureproof ketones is largely hydrocarbon carbon, but

may contain the usual modifying groups, such as hydroxyl, halogen,ester, etc., providing it has a sufficiently high hydrocarbon carboncontent to offset the affinity for water for those sub- .stituentgroups. In so far as this specification is concerned, a hydrocarboncarbon atom is one which has at least three of its valences attached tocarbon or hydrogen.

When an organic mono-ketone containing no modifying group in themolecule is used as the moistureprooflng agent, we have found that themolecule must contain at least 20 hydrocarbon carbon atoms in thehydrocarbon portion thereof for the carbonyl group in order to achieve amoisturcprooilng effect. When more than 20 hydrocarbon carbon atoms arepresent, better moistureprooflng effects are secured.

The ketones contemplated by the instant in vention may be aliphatic oraromatic or mixed aliphatic aromatic, or cyclic or substituted ketonescontaining additional active or modifying groups. Any group or atomother than hydrocarbon is considered an active group. We have foundthat, when the number of active groups is increased, for example, whentwo similar active groups are present, the limiting ratio may be 55%-66%of the limiting ratio for one such group, while for three similar activegroups the limiting ratio is 45%-55% and approaches a limiting value of30% as the number of similar active groups is further increased. Whendifferent active groups are introduced, the limiting ratio ofhydrocarbon carbon atoms will vary, depending on the nature and numberof such groups. Thus, for example, if two. difierent' active groups arepresent, the limiting ratio of hydrocarbon carbon atoms to active groupswill be 55%-66% of the meanof the limiting ratios for each of theindividual active groups.

The following are specific illustrative examples of organic ketoneswhich are moistureprooi and can be utilized in the preparation ofmoisture- Stearone (Ci-zI-Lza)zCO- di-heptadecyl ketone Cerotone..(Cz5Hsi) zCO di-pentakosyl ketone As previously mentioned, thecomposition also contains a film-forming substance. As illustrativeexamples of film-forming substances may be mentioned cellulosederivatives, for example, cellulose nitrate, cellulose acetate, ethylcellulose, benzyl cellulose, mixed esters or ether esters; resins,either natural or synthetic, such as rosin, hydrogenated rosin and itsderivatives, including glycerol, glycol or diethylene glycol esters ofhydrogenated rosin; rosin esters of glycerol, glycol or diethyleneglycol; gum dammar; polybasic acid-polyhydric alcohol resins, eithermodified or unmodified; vinyl resins of the polymerized vinyl acetate,polymerized chlor-vinyl acetate and polymerized vinyl acetal resintypes; metastyrene resin; phenolic condensation products; rubber,gutta-percha, balata caoutchouc; synthetic rubbers including polymers ofisoprene, butadiene and their homologues; chemical derivatives ofrubber, such as halogenated rubber, rubber treated with sulphuric acid,rubber treated with tin tetrachloride; rubber treated with chlorostannicacid, varnishes, etc. One or a plurality of film-forming ingredients maybe used. The precise film-forming ingredient or mixture thereof dependsupon the purpose for which the compositions are to be used.

When the composition contains a softener, any suitable softener for thefilm-forming ingredient may be used. I For example, diamyl phthalate,tricresyl phosphate, dicyclohexyl phthalate, butyl benzoyl benzoate,etc. may be used, when the film-forming ingredient is a cellulosederivative.

In some compositions wherein a cellulose derivative is used, the filmwhich is produced may be hazy. If desired, this may be overcome byincorporating in such a composition a blending agent. Such compositions.also are generally more moistureprbof than those without the blendingagent or gum. The blending agent tends to improve the compatibility ofthe moistureproofing agents with the other ingredients in t e film andconsequently the impermeability of the film. As several illustrativeexamples of blending agents may be mentioned gums or resins, such asdammar, gum 'elemi, ester gum, hydrogenated rosin; hydrogenated estergum or the like, halogenated diphenyl, a natural occurring balsam or asynthetic balsam-like substance, such as diethylene glycolhydrorosinate, or a substance such as lanum, hydrogenated castor oil,di-dodecyl phthalate, retene, diricinoleic ester of glycerol or thelike.

The ingredients which constitute the final film may be dissolved in anappropriate solvent or solvent mixture to form a solution which may beused as herein described. Alternatively, the ingredients constitutingthe final film may be used in the form of a melt. When the compositionis to be used in theform of a melt, it is desirable to include therein ablending agent to inhibit crystallization. Hydrogenated rubber,hydrogenated ester gum, rosin, dammar, diethylene glycol hydrorosinateand the like, are several illustrative examples of crystallizationinhibitors. Whenever the composition is in the 2,093,537 form of alacquer and used for coating purposes,

the solvents thereof are chosen so that they will not produceany'deleterious eifects on the base being coated. l

The proper formulation of the lacquer so that it will yield coatingswhich are transparent and highly moistureproof is determined by tests.One of the most important things to be determined is the properamount ofblending agent to be used. This can be determined, for example, asfollows: A series of compositions is prepared containing the sameamounts of lacquer base,. softener, moistureproofing agent and solvent.Difierent quantities of blending agent are then added to each of theselacquers and the general properties, such as transparency and thepermeability values of sheets of regenerated cellulose, for example,coated with each of these compositions, are plotted against the ratio ofblending agent to moistureproofing agent used.

When a lacquer of the type described in Example III is modifiedaccording to this systemfor different blending agents with the samemoistureproofing agent.

atic procedure, it will be found that the lowest permeability valueoccurs very near the point where the coatings become completelytransparent. In the ease of stearone in this particular composition,this point is equivalent to approximately 3.25 to 6 grams of dammar to 1gram of stearone. It is obvious that this optimum blendingagent-moistureproofing agent ratio will vary, for differentmoistureproofing agents and In general, this ratio depends upon. thehydrocarbon carbon contentand the solubility of the moistureproofingagent in the lacquer solids. Thus, the ratio is high formoistureproofing agents having high hydrocarbon carbon content and lowfor moistureimportant ones.

- of moistureproofing agent),

proofingagents which are quite soluble or compatible with the otherconstituents of the coatmoistureproofing agent ratio determined forsheets of regenerated cellulose coated with a series of lacquers-havinga difierent lacquer base- 'moistureproofing' agent ratio to whichvarious amounts of. dammar or other blending agent' have been added.These relations will-have the same general character but it will befound generally that, as the lacquer base-moistureproofing agent ratiois increased (decreasing the quantity the permeability values will behigher for a given blending agentmoistureproofing agent ratio and willeventually pass out of the moistureproof limit. on the other hand,decreasing this ratio (increasing the moistureproofing agent) does notdecrease the permeability values indefinitely and, after a certaln pointis reached, may even decrease the moistureproofness. Experiments haveshown that the optimum lacquer bas-moistureproofing agent ratio usuallyfalls within the limits 1:10 to 200:1 and the blendingagent-moistureproofing agent ratio lies between the limits 0:1 to 10:1.The most satisfactory cellulose deriva'- tive base-moistun'uproofingvlacquers generally fall within these limits for nearlyallmoistureproofing agents, the optimum pyroxylin-moistureproofingagentratiosbeing of the order of 2:1 to 30:1. However, forcertain purposes,for

example, compositions for casting moistureproof foil, the ratios maydiffer greatly from those given above'and we do not intend that weshould be confined to these limits which are suggested merely as an aidto the proper formulation of molstureproofing lacquers.

The above or any other method for determining the most satisfactoryformula in which to use any moistureproofing agent to achieve mini-.-

will be formulated differently into various dopes or vehicles. There isthus no single composition such as has been described above which iscapable of universal application. The specific examples hereafter .givenare thus illustrative, and the I above-described method ofsystematically varying the compositions of solids in which amoistureproofing agent is used is exemplary of a general method, wherebyoptimum results may be achieved with an agent. The method is, of course,capable of extension to'include variations of any of the solid lacqueringredients,- or even to include solvents and the solvent composition.Thus, when ,one skilled in the art is taught by these disclosures, hewill be able to formulate a variety of compositions containing any ofthe moistureproofing agents or to determine those compositions withwhich our moistureproofing agents are most advantageously used. Amoistureproofing agent is thus not a material which will always anduniversally produce moistureproof coatings utterly regardless of thecomposition in which it is used. It usually r res to be formulated incertain favorable compositions to bring out its inherentmoistureproofing properties. on the other hand, a substance which isnotinherently moistureproof cannot by any extended amount of work informulation be made toyield moistureproof films or coatings. Thus, whenwe speak of the inherent property of a compound to moistureproof, we areconcerned with a specific inherent property which permits it to be usedwith some film-forming vehicle to produce moistureproof coatings.

The composition can be used for the production of films, either bycasting it in the well:

known manner to produce self-sustaining films,

or by coating it on to the selected base. When the composition is to beused as a coating, any suitable base materiaLvpaper, highly calendered.

paper, glassine, leathenfabrics, etc. may be used. The compositions mayeven be applied to metals to prevent them from rust by virtue of theirmoistureproofing property. They may also be used to coat individualfibers of cotton, wool or artificial silk in such a manner as to makethem moistureproof. In the preferred embodiment of the invention, when atransparent wrapping tissue is desired, the base may consistof thin,dense,

non-fibrous, substantially non-porous and pref'erably transparentsheeting formed of .a cellulosic, aibumi-nous or other material. Asillustrative examples of ceilulosic sheeting may be mentioned cellulosicsheeting coagulated or precipitated from an aqueous dispersion orsolution of a cellulosic material, for example, sheeting of regeneratedcellulose, glycol cellulose, cellulose glycolic acid, lowly etherifledor esterified cellulose, such as lowly methylated cellulose; andsheeting of cellulose derivatives, such as cellulose acetate, cellulosenitrate, ethyl cellulose, benzyl cellulose.

' Gelatin and casein, hardened or not as desired,

are mentioned as illustrative examples of albuminous materials.

When a selected base, as for example regen- 110" C., in order to preventseparation or crystallization of the moistureprooflng agent duringevaporation of the solvent; It is also preferable to use air low inmoisture content during the drying operation in order toobtainevaporation of the solvent without film blush. After being dried, theproduct, if the base is of the type which loses moisture at elevatedtemperatures, may be subjected to a humidifying treatment or other meansfor sufficient time to impart or restore flexibility and to deodorize.In some cases, the

lacquer-coated materialsmay be air-dried at room temperature, in whichcase the humidifying treatment is not needed.

Hereafter, there are set forth several illustrative specific examples inorder to more clearly explain the invention:

Example I (A) A composition consisting of the following ingredients inapproximately the proportions set forth is prepared in any convenientand appropriate manner:

Parts by weight Pyroxylin 5.26 Gum dammar 3.25 Dibutyl phthalate 2.32

Laurone 1.00

Ethyl ac 40.25 Toluene 36.00 Alcohol 628 Acetone 0.68.

A transparent sheet of regenerated cellulose is submerged in thislacquer which, for conven ience, is maintained at a temperature of 40 C.in order to prevent separation of the moistureq proofing agent. Theexcess lacquer is removed by suitable means and the coated sheet isdried, preferably promptly, at an elevated temperature and preferablyalso in air at 90 C.-110 (2.: The

coated sheet is glass-clear in transparency, flexible, non-tacky,glossy, possesses good surface slip and" is only approximately 0.00005"to 0.00015" thicker than the uncoated sheet and it is practicallyimpossible to distinguish the coated sheet from the uncoated sheet inappearance.

However, the coated sheet is moistureproof having a permeability valueless than 570. for example, of the order of 200 or less.

The coated sheet is much more resistant to the passage of water vaporthan a similar sheet coated with the same lacquer, except for theomission of laui'one, or a sheet coated, for exam-- pie, with a highgrade waterproof spar varnish. A sheet coated with the lacquer withoutthe addition of laurone will have a permeability value of 4,000 to5,000, while a sheet coated with a waterproof spar varnish will have apermeability value from 2,000 to 4,000,

(B) Laurone is substituted by an equal amount of stearone in ExampleI(A) above. The proces of Example I(A) is utilized forcoatingtransparent regenerated cellulose sheeting. The product possessesthe same characteristics as the product of Example I(A).

(C) In Example I(A) substitute laurone by an equal amount of myristone.The process of Example I(A) is used to coat transparent regener'atedcellulose. The product possesses the same properties and characteristicsas that of Example I(A), except that the product produced by the instantexample has a permeability value of the order of 285.

Example II A composition consisting of the following ingradients inapproximately the proportions set forth is prepared by any well-knownprocedure:

Parts by weight Ethyl cellulose 6.0 Rosin 3.6 Tricresyl phosphate 1.0Laurone 1.0 Toluene 60.0 AlcohoL- 19.0

Transparent sheets of cellulose acetate are coated in the mannerdescribed in Example HA). The product is transparent, flexible, glossy,and possesses good surface slip. It has a permeability value of theorder of 235 or less.

The above composition becomes useful for airdried coatings if 10 partsby weight of ethyl lactate are added thereto to avoid blushing.Compositions of this type may be used for protecting steel and otherccrrodible metals against rust and the like. These coatings may beair-dried at room, temperature for 20 minutes and are at least 20 timesas impermeable to moisture vapors as similar coatings containing nomoistureproofingagents.

As previously explained, in many cases it may be desirable to omit thegum or resin entirely, though when used it may materially improve thetransparency of the final product.

The following are examples of moistureproofing compositions containingno gum or resin:

Example III A composition consisting of the following ingredients inapproximately the proportions set forth is preparedin any well-knownmanner:

Parts by weight Regenerated cellulose thinly coated with this lacquerutilizing the procedure set forth in Example HA) and dried at 90'(Lt-110 C. will have a permeability value of the order of 150 or less.

. compositions trample I? A composition consisting of the followingingredients in-approximately the proportions set fo'rth is, prepared inany well-known manner:

Transparent sheets of cellulose acetate coated as described underExample I(A) and dried at 90 (IL-110 C. will have, a permeability valueof 570 or less. l

The compositions described in Examples 111 and IV yield coatings whichmay be slightly hazy. If transparency is essential, a blending agent ofthe type previously mentioned may be incorporated in these compositions.'lhus, for example, the lacquer described in Example 111 may be'somodified that it always will yield transparent coatings by the additionof a blending agent, such as damrnar. The quality of dammar or otherblending agent to be added must be determined as previously described.

The following is an example of a composition wherein a polybasicacid-polyhydric alcohol resin constitutes the film-forming ingredient.composition consisting of the following ingredients in approximately theproportions given is prepared in any suitable manner:

I Partsby weight *Perilla oil polybasic acld-polyhydric-alco- Vhol.resin varnish u, 50.0 Stear n 1.0 Tolu 50.0

ierilla oil polybasic acid-polyhydric alcohol resin varnish is preparedfrom the following ingredients:

I Parts by weight Perllla oil 329.0 Phthal-ic anhydride 472.5 Glycerin204.6 Sodium hydl'nnide 0.7

Metallic cobalt (added as linoleate); 0.7 Ethylabeta 800.0

The procedure for preparing the perilla oil polybasic 'acid-poiyhydricalcohol resin vamish is as follows: Heat 72.6 parts of C. P. glycerint'o 350 F. in closed kettle-condenser and stirrer.

At 350 F. add NaOH, followed by perilla oil. Stir rapidly andheat to 437F. Hold until clear (15-30 minutes). Add phthalic anhydride and heat to392 F. Add residue of glycerin to batch. Heat to 392 F. and hold (5hours). Acid number 45-55. Cool to 175 F. Cut with ethyl acetate. Adddrier and centrifuge. (Solids 50%.)

Regenerated cellulose sheeting coated with this composition, explainedunder Example 1(A) and dried at room temperature or at 90 .-ll C.produces a product having a permeability value of the order of 150 orless. A composition of this type may be used without a blending agentbut in some cases it is advantageousto use a small amount of gum.Usually, compositions of this nature are sufiiciently flexible withoutthe use of a plasticizer. Lacquers of this type may be used whenparticularly good adhesion is desired.

As previously mentioned, another method of obtaining articles which areof themselves moistureproof is the casting of films containing theorganic ketones as moistureprooflngagents. The

given in Examples 1,11, m and IV inclusive may be used for this purpose..It is usually desirable, however, to employ a higher solids basesolution forwcasting sheets than is 'ordinarily'used for forming thincoatings. Furthermore, in view of the greater thickness of cast foils ascompared to coatings, a smaller proportion of the moistureprooflng agentis used in order to obtain transparency and a high degree ofmoistureproofne'ss, and this in turn will require the use of a smallerquantity of blending agent and/or the use of blending agents other thanhard gums in appreciable quantities. Those skilled in the art will beable to formulate by tests satisfactory compositions for the preparationof cast sheets.

The cast sheets and protective coatings prepared in accordance with theinstant invention have the ability to resist the transmission ordiffusion of water vapor to an extent at least 4 times that displayed bysheets of equal thickness and produced from similar or prior artcompositions formulated without the addition of moistureprooiing agents.The value 4 merely sets forth the minimum improvement and does not Thecompounds described in this application as moistureprooiing agents havemanyadvantages. Moistureprooflng compositions containing themoistureproofing agents are easily duplicated. As previously stated,these compositions in cer-' tain formulations thereof yield coatingswhich air-dry at ordinary temperatures. For certain purposes where it isnot feasible to force-dry the coatings, this becomes especiallyimportant. As for the moistureproofing agents themselves, they aregenerally colorless, odorless, tasteless, nonvolatile, and essentiallynon toxic, at least in the quantities in which they are used; and theycan be reproduced synthetically with a high degree of uniformityandconsistency.

In the definition hereinbefore set forth, it is to be understood thatthe permeability value of 570 maximum value. In many represents only the235, 140, 5'7, 30 or indeed cases permeabilities of less may beobtained.

When bases of the preferred type are utilized, the ultimate product isadmirably suited for use as a transparent moistureproof wrapping tissue.

Since it is obvious that various changes and modifications may be madein the above description without departing from the nature or spiritthereof, this invention is not restricted thereto except as set forth inthe appended claims.

We claim: 1. An article of manufacture having an unbroken continuousransparent moistureproof surface comprising a. film-forming substance, a

solid organic ketone having a melting point of at least 37 C. as themoistureprooflng agent and a blending agent, said ketonei containing nomodifying groups in the'molecule and having at least 20 hydrocarboncarbon atoms for the carbonyl group and beingpresent in an amount toimpart moistureproofness to said article.

2. An article of manufacture comprising an unbroken continuous.transparent 'moistureproof flimcomprising a film-forming substance, asolid organic ketone having a melting point of at least 37 C. as themoistureprooflng agent and a blending agent, said ketone containing nomodifying groups in the molecule and having at least 20 hydrocarboncarbon atoms for the carbonyl group and being present in an amount toimpart moistureproofness tosaid article. I

3. An article of manufacture comprising an unbroken continuoustransparent moistureprooi' film comprising pyroxylin, a solid organicketone having a melting point of at least 37 C.- asthe moistureprooflngagent and a blending agent, said ketone containing no modifying groupsin the molecule and having'at least 20 hydrocarbon carbon atoms for thecarbonyl group and being present in an amount to impartmoistureproofness to said article, the ratio of the quantity ofpyroxylin to the quantity of ketone being within the limits of 2:1 to :1and the ratio of the quantity 0! blending agent to the quantity ofketone being within the limits of 3.25:1 to 6:1;

4. An article of manufacture comprising a transparent, flexible,non-fibrous base sheet or film having an unbroken continuous transparentmoistureproof flexible non-tacky coating comprising a film-formingsubstance, a solid organic ketone having a melting point of at least 37C. as

the moistureprooflng agent and a blending agent,

said ketone containing no modifying groups in the molecule and having atleast 20 hydrocarbon carbon atoms for the carbonyl group and beingpresent in an amount to impart moistureproofnest to said article.

5. An article of manufacture comprising a transparent, flexible,non-fibrous base sheet or film having an unbroken continuous transparentflexible non-tacky coating comprising the following ingredients in theapproximateproportions set forth:

Parts by weight Pyroxylin. 5.26 Gum dammar 3.25 Dibutyl phthalate 2.32Laurone 1.00

6. An article of manufacture comprising a transparent, flexible,non-fibrous base sheet or film having an unbroken continuous transparentflexible non-tacky coating comprising the following ingredients in theapproximate proportions set forth:

Parts by weight Pyroxylin 5.26 Gum dammar 3.25 Dibutyl phthalate 2.32Btearone 1.00

7. An article or manufacture comprising a transparent, flexible,non-flbrous base sheet or film having an unbroken continuous transparentflexible non-tacky coating comprising the 101- lowing ingredients inthe'approximate proportions 8. An article of manufacture having anunbroken continuous transparent moistureproof surface comprising afilm-forming substance, a.

solid. organic ketone having a melting point of at least 37 C. as themoistureprooflng agent, and

a blending agent, said ketone containing no modifying groups in themolecule and being seand (4) ketones containing more than 3 carbonylgroups and having at least 6 hydrocarbon carbon atoms for each carbonylgroup, said ketones being present in an amount to impartmoistureproofness to said article.

' 9. An article of manufacture comprising an unbroken continuoustransparent moistureproof film comprising a film-forming substance, asolid organic ketone having a melting point of at least 37 C. as themoistureprooflng agent, and a blending agent, said ketone containing nomodifying groups in the molecule and being selected from the group whichconsists of (l) mono-ketones having at least 20 hydrocarbon carbon atomsfor the carbonyl group, (2) di-ketones having at least approximately 11hydrocarbon carbon atoms for each carbonyl group, (3) tri-ketones havingat least approximately 9 hydrocarbon carbon atoms for each carbonylgroup, and (4) ketones containing more than 3 carbonyl groups and havingat least 6 hydrocarbon carbon atoms for each carbonyl group. saidketones being present in an amount to impart moistureproofness to saidarticle.

10. An article of manufacture comprising a non-fibrous transparent basesheet or film having an unbroken continuous transparent moistureprooicoating comprising a film-forming substance, a solid organic ketonehaving a melting point of at least 37 C. as the moistureproofing agent,and a blending agent, said ketone containing no modifying groups in themolecule and being selected from the group which consists of (1)mono-ketones having at least 20 hydrocarbon carbon atoms for thecarbonyl group, (2) diketones having at least approximately llhydrocarbon carbon atoms for each carbonyl group, (3) tri-ketones havingat least approximately 9 hydrocarbon carbon atoms for each carbonylgroup, and (4) ketones containing more than 3 carbonyl groups and havingat least 6 hydrocarbon carbon atoms for each carbonyl group, saidketones being present in an amount to impart moistureproofness to saidarticle.

WILLIAM HALE CHARCH. MERLIN MARTIN BRUBAKER. FREDERICK M. MEIGS.

